My reading is that it is all attacks you make over the course of the next round.
But there is an area that I find even more unclear in the feat, and that is do you get the bonus against the foe if any of the attacker's attacks miss or only if all of the opponent's attacks miss. The first part of the feat's wording seems to indicate the former, but then the closing sentense seems to clarify in favor of the latter.
My ruling is that bonus is only gained if all of the attacker's attacks miss, but I'd be interest to here either confirmation or a contrary opinion and explanation.